When, for example, a stadium for ice hockey game as shown in FIG. 1 is used as a stadium for a basketball game as shown in FIG. 2, with a basket court 50 arranged at the center area, it would be desirable to be able to accommodate as increased number of spectators as possible. In this instance, in addition to the existing tiered stands 51 in the stadium, it has been a conventional practice generally adopted in the United States or in other countries to arrange separate stands 52 between the existing stands 51 and the basket court 50 as seen in the longitudinal direction of the stadium. The same is true when, for example, an athletic stadium is to be used as a concert hall by removing part of the tiered stands on one longitudinal side of the stadium and arranging a stage 53 on that side, as shown in FIG. 3.
When a stadium is used for various purposes as exemplified above, it is preferred that the inclination of the tiered stands as a whole can be changed as required in relation to the intended use. Thus, in the above-mentioned examples, in order to watch an ice hockey game, it is desirable to achieve a steep inclination of the stands and thereby realize a wide visual field, as shown in FIG. 4(a) which is a schematic sectional view of the tiered stands. On the other hand, for watching a basket ball game, in view of the fact that the basket court itself is not large, and by further taking into account the required number of the additional stands, it is desirable to achieve an intermediate inclination by increasing the height of the tiered stands on the lower side. Furthermore, when the stadium is used as a concert hall, it is highly important that as many stands 52 as possible are arranged on the front side of the tiered stands 51. Thus, the height of the tiered stands 52 on the lower side is further increased as shown in FIG. 4(c) to achieve a less steep inclination.
In the examples shown in FIGS. 3 and 4(c), the tiered stands 51 situated on the side of the stage 53, either partly or in their entirety, may be arranged such that they are of a telescopic structure wherein the floors on the lower side are retraced below the floors on the upper side, thereby allowing the stage 53 to be installed. However, since such an arrangement, per se, is not a direct subject matter of the present invention, a detailed explanation will be omitted.
The inclination of the tiered stands 51 as a whole can be readily changed, for example, in the manner as shown in a schematic side view of FIG. 5(a). In this instance, among the horizontal floor members F.sub.1 to F.sub.n arranged in the form of tiers, the location corresponding the rear end of the floor member F.sub.n at the uppermost stage is used as a fulcrum O, and a linear frame member FR connected to the rear ends of the remaining floor members F.sub.1 to F.sub.n-1 is caused to rotate about the fulcrum O by a desired angle upwards, for example. During such rotation, the horizontal posture of the movable floor members F.sub.1 to F.sub.n-1 can be maintained by providing a parallel link mechanism such that movable portions associated with the respective floor members are restricted with respect to each other. To this end, as shown in FIG. 5(b) for example, the floor members F.sub.1 to F.sub.n including the stationary floor member are connected to each other by a link element LN which extends in parallel with the frame member FR.
When, however, the overall inclination of the tiered stands and hence that of the plurality of floor members is changed in the manner explained above, as shown in FIG. 5(a), the floor member F.sub.1 at the lowermost stage protrudes forwards by a relatively large horizontal distance P along with a decrease in the inclination, so that the projected planar space of the stands in their architectural design cannot be maintained constant. Also, when it is necessary to provide a stationary structure, such as fence, in front of the floor member F.sub.1 at the lowermost stage, as in ice hockey stadium, there still remains a problem that the floor member F.sub.1 at the lowermost stage is brought into interference wit such a stationary structure.
With the above-mentioned known arrangement, furthermore, the depth of each tier increases as the inclination becomes less steep, thereby giving rise to a problem that it is at any time difficult to optimize the desired level difference between the tiers, the desired location and the desired height of the seats provided on each tier, hence the eye position and visual field of the spectator on the seat.
Therefore, it is an object of the present invention to provide variable floor height tiered stands in which longitudinal displacement and variation in depth of the tiered floor member of the stands are minimized when the inclination of the tier floor members is changed, thereby allowing planning of the tiered stands with a constant installation space, and eliminating the risk of interference between the stands and any stationary structure, while facilitating settings of the desired level difference between the tiers, the desired location and the desired height of the seats provided on each tier, and the like.